This invention relates generally to waste heat recovery systems and, more particularly, to a system for recovering waste heat from engine exhausts having corrosive elements therein.
Waste heat produced by a wide range of engines and industrial processes can be harnessed to provide benefits such as electricity, cooling, and water heating. Waste heat is often present in the form of a hot gas flow which is sometimes contaminated by corrosive elements such as sulfur and chlorine. These elements are relatively benign at elevated temperatures where they remain in gaseous form, but on cooler surfaces the gas may condense and cause acid dewpoint corrosion (ADC).
Interconnection of hot gas waste heat streams is often constrained by the existence of ADC. For example, to operate some waste heat recovery device it may be desirable to combine the exhaust streams of two reciprocating engines burning moderate sulfur fuel. If both engines are operating, then ADC is not present because the engine components and exhaust pipes are all above the dewpoint temperature. This situation changes when one of the engines is disabled. Now, higher pressure at the exhaust stack of the operating engine exhaust will cause backflow of exhaust into the cold, nonoperational engine. Condensation and corrosion can progress quickly on the cold surfaces.